The gunman who fatally shot a migrant during a rampage at an ICE facility disclosed his motive in a handwritten note and had been obsessively searching for footage related to the “Charlie Kirk assassination” in the days before his attack, according to the FBI.

Joshua Jahn, 29, made numerous online inquiries about ballistics and the “Charlie Kirk Shot Video” in the 48 hours leading up to Wednesday’s shooting in Dallas, FBI Director Kash Patel stated on X.

The gunman’s obsession with Kirk’s shooting was revealed on his devices and through raids on his home and bedroom, Patel said. 

Inside Jahn’s residence, Patel reported finding a handwritten message left by Jahn. The note read: “Hopefully this will give ICE agents real terror, to think, ‘is there a sniper with AP rounds on that roof?'”

Jahn had downloaded a document titled Dallas County Office of Homeland Security & Emergency Management, which contained a list of DHS facilities. 

Jahn had also searched for apps that track ICE agents for a week before he launched his horror attack, Patel said. 

‘Further accumulated evidence to this point indicates a high degree of pre-attack planning,’ Patel concluded. 

It comes after Patel previously shared an image of the bullets used in the shooting on the ICE facility, which showed shells engraved with blue ink reading: ‘Anti-ICE’

Jahn, 29, was named as the gunman who opened fire on the ICE detention center around 7am Wednesday morning, before killing himself as cops descended on him.

Law enforcement said that the sniper perched on a roof adjacent to the facility and rained bullets on the migrants as they were being transported in an unmarked ICE van. 

After Jahn was identified as the alleged shooter, his brother Noah told NBC News that he did not believe his brother was especially interested in politics and had not voiced his opinions on immigration before.

‘He didn’t have strong feelings about ICE as far as I knew,’ his brother said.

Noah said his younger brother was unemployed but had previously worked as a coder, and was planning on moving in with their parents in Oklahoma.

Jahn has been pictured in a mugshot from his arrest in 2015, when he was hit with felony charges for delivering marijuana in an amount greater than 1/4 ounce.

He was a registered independent in the 2024 election, but last voted in the Democratic primaries in March 2020, records showed.

The alleged shooter’s brother reportedly spoke before he knew that his brother had been identified as the sniper, and described him as ‘unique’ without elaborating.

‘I didn’t think he was politically interested,’ he continued, saying he had last seen him two weeks before the shooting on Wednesday and nothing seemed unusual.

‘He wasn’t interested in politics on either side as far as I knew.’

The siblings grew up in Allen, Texas, and spent their childhoods attending the Boy Scouts, the brother said.

He added that his brother knew how to use a rifle that his parents owned, but insisted that ‘he’s not a marksman, that’s for sure.’

Asked about the ICE facility shooting, he remarked: ‘He would not be able to make any shots like that.’

As investigators descended on the scene in Dallas, images showed a poster taped to the side of a vehicle believed to belong to Jahn.

A sign with what appears to be black splatter on the car reads: ‘Radioactive fallout from nuclear detonations that’ve passed over these areas more than 2x since 1951.’

Investigators said Jahn fired ‘indiscriminately’ at the ICE office, peppering the transport van with bullets and also hitting windows in the building numerous times.

Witness Arianny Sierra told NBC that she was in her car waiting for her husband to return from an ICE appointment in the facility when she heard shots ring out.

‘The shots began at around 6:10 a.m. There were like 20 shots in a row,’ she said.

The victims were ICE detainees, and no law enforcement were injured in the shooting. Officials said at a press conference on Wednesday morning that the sniper opened fire ‘from an elevated position’ as migrants were inside the transport van.

He is believed to have been found on the roof of a nearby immigration attorney’s office, WFAA reported.

Patel said in an X post at the time: ‘While the investigation is ongoing, an initial review of the evidence shows an ideological motive behind this attack.

‘These despicable, politically motivated attacks against law enforcement are not a one-off.’